1. Field of the Invention
The present invention relates to a temperature control method for controlling the temperature of a hot plate, so that respective measured temperatures of the hot plate at a plurality of measurement points conform to respective target temperatures. This method is adopted in a heat processing apparatus for performing a heat process on a substrate placed on a hot plate, which is used in a coating/developing system for applying a resist coating onto a substrate, such as a semiconductor wafer, to form a resist film and then performing development on the resist film after light exposure. The present invention further relates to an adjusting apparatus, a temperature controller, a program, a storage medium, and a heat processing apparatus, which are suitably compatible with the temperature control method. Particularly, the present invention relates to a suitable technique for suppressing a variation in temperature during a transient time.
2. Description of the Related Art
In the sequence of photolithography for semiconductor devices, a resist is applied onto a semiconductor wafer to form a resist film. Then, the resist film is subjected to a light exposure process in accordance with a predetermined circuit pattern. Then, the light-exposed pattern thus formed is subjected to a developing process to form a circuit pattern on the resist film. During this sequence, various heat processes are performed, such as a heat process (pre-baking) after resist coating, a heat process (post-exposure-baking) after light exposure, and a heat process (post-baking) after development.
The resist coating, the development after light exposure, and the heat processes described above are preformed by a resist coating/developing system which includes a plurality of processing units for performing these processes and transfer units for sequentially transferring wafers to perform a series of processes.
In general, a heat processing unit for performing a heat process in this coating/developing system is structured to perform a heat process on a target substrate, such as a semiconductor wafer, placed on a hot plate, which is provided with a heater and a temperature sensor built therein to control the temperature to be a target temperature (for example, Jpn. Pat. Appln. KOKAI Publication 11-067619).
Conventionally, in a heat processing unit of this type, the temperature of the hot plate is controlled to be uniform, so as to uniformly perform a heat process without a variation on a circular semiconductor wafer by the hot plate. However, for example, in a transient time when the semiconductor wafer is placed on the hot plate and the heat process is started, even if the temperature of the hot plate is uniformly controlled, the temperature of the semiconductor wafer is not equal to the temperature of the hot plate. Further, the semiconductor wafer tends to release heat more at the peripheral portion than at the central portion on the surface, and a variation in temperature is generated on the surface of the semiconductor wafer. In addition, a number of heat processing units are disposed in one resist coating/developing system, and include individual differences among them, so the temperature of substrates heated by heat processing units suffer a variation in temperature depending on the units.
As described above, conventionally, even if the temperature of a hot plate is controlled to be in a desired state, the temperature of the semiconductor wafer can be hardly set in a desired temperature state.